The present invention relates to a blast deflector, and in particular, but not exclusively, to a jet blast deflector for use on a sea vessel.
Jet blast deflectors, as provided on the flight deck of aircraft carriers, are arranged to deflect the jet blast (eflux) upwardly when an aircraft is preparing to take-off, so as to protect aircraft and personnel from the eflux. However, conventional jet blast deflectors create numerous difficulties. The hot gases which result may create difficulties for aircraft which fly through the updraft of hot air, due to the decreased lift available in the hot air. Thus, during and following use of the deflector for an aircraft taking-off, aircraft must not fly in the vicinity of the deflector until the hot gases have dispersed.
The deflector is formed from an area of the deck which may be raised as required. As the surface of the deflector may be exposed to temperatures in the region of 1600xc2x0 C. it is necessary that the deflector be water cooled. However, even with the aid of water cooling, it takes some time for the surface of the lowered deflector to cool sufficiently before it can be used safely as deck surface once more.
It is, therefore, amongst the objectives of an embodiment of the present invention to provide a jet blast deflector to obviate or at least mitigate at least one problem associated with the prior art.
According to a first aspect of the present invention, there is provided a jet blast deflector for location on a flight deck of a sea vessel, the jet blast deflector comprising a deflector member adapted to deflect eflux created by the blast of a jet engine of an aircraft downwardly and beneath the deck of the vessel.
In use, the present invention enables eflux to be directed away from the flight deck area therefore safeguarding personnel and other aircraft from the eflux generated by the aircraft during take-off. In addition, the invention provides the added advantage of directing hot gases away from the area directly above the vessel, and thus from the flight path of landing aircraft, thereby providing a relatively clean undisturbed airflow over the flight deck area.
Preferably the deflector member is moveable between a lowered or retracted configuration and a raised or extended configuration. In the retracted configuration a portion of the member may form a section of a deck area of the vessel. In the lowered configuration an upper surface of the member preferably lies flush with the deck area of the vessel, in order that personnel and aircraft may be transported over the member. Most preferably, in the raised configuration an underside or lower surface of the member is exposed to the eflux, and may be utilised to deflect the eflux generated by the jet engine of the aircraft below the deck surface.
By presenting the underside of the member to the eflux, exposure of the non-skid paint typically found on flight decks, and coated on a topside of the member, to the direct heat of the eflux is prevented. This is particularly useful as conventional non-skid paints deteriorate on exposure to high temperatures.
The jet blast deflector may include one or more baffles so as to help contain and direct the eflux. End baffles may assist in preventing the eflux from passing around the ends of the member. The baffles may be angled towards a centre of the deflector member, in order to help direct the eflux below the deck. Baffles may be provided intermediate the ends of the member.
The underside of the deflector member may be of a curved or concave shape; this form is preferred for dealing with eflux that is generated at sub-sonic speed, whilst for eflux travelling at supersonic speed it is preferred to have a planar surface, to provide for xe2x80x9creflectionxe2x80x9d of the eflux as it contacts the surface of the member. Of course in many instances it may be necessary to configure the underside as a compromise between deflecting both sub-sonic and supersonic flow.
Preferably, the jet blast deflector comprises actuation means for raising and lowering the deflector member. The actuation means may be hydraulic, although any appropriate means of actuation may be utilised, including pneumatic or electrically powered means. The actuation means may be coupled to end baffles of the deflector member, and may be adapted for location below the deck of the vessel.
The deflector member may comprise several sections that may be independently controlled such that the sections may be raised and lowered independently.
Preferably, the deflector further comprises a duct, channel or other conduit, to carry eflux redirected by the deflector beneath the deck, and most preferably to an outboard side of the sea vessel.
Preferably, the duct is adapted to run substantially parallel to the deck of the vessel.
Preferably also, an outlet end of the duct is located in an outboard side of the hull of the vessel.
Further preferably, the duct comprises cooling means for cooling at least one of the eflux and the duct. The eflux will thus be cooled as it passes through the duct before being vented outboard of the vessel. The cooling means may include nozzles to deliver a spray of water or other fluid to cool the eflux.
The duct may include means for creating an airflow or draft, in order to draw the eflux into the duct, and said means may include a fan, jet pump or the like.
The deflector member may incorporate conduits or a water jacket arrangement through which a coolant may be passed, so as to dissipate heat generated on the underside of the member by the eflux.
Alternatively, or in addition, the underside of the deflector member may comprise a passive heat shield. The heat shield may comprise high density ceramic tiles.
Preferably, the underside and topside of the deflector member are separated by thermal insulation, such that the topside of the member is not subjected to the high temperatures experienced by the underside of the deflector member. This provides the added advantage of maintaining the topside of the member relatively cool, such that as soon as the member is lowered the topside is cool enough for personnel and equipment, such as aircraft, to be immediately moved across the surface of the member.
Preferably, the deflector comprises a grill or guard such that when the deflector member is in a raised position the grill provides a safety barrier to help prevent personnel and other objects from falling beneath the deck.
The jet blast deflector may include a locking mechanism to ensure that the deflector member remains in a retracted or lowered position when not in operation.
According to a second aspect of the present invention, there is provided a method of channelling eflux, generated by a jet engine of an aircraft located on the deck of a sea vessel, the method comprising directing the eflux below the deck and outboard of the vessel.
Preferably the method includes the step of cooling the eflux.